Today’s moviegoers know that many breathtaking special effects are created by powerful computers. What they often don’t know is that these scenes still require a lot of work and preparation by creative people.

With every blockbuster season, visual effects in Hollywood action movies are getting more realistic and believable. That's because the work is no longer done solely by computer enthusiasts, says Aron Hjartarson, executive creative director of the London-based visual effects company Framestore.

“But it's progressed now and now it's actually real artists that are really good at their job, like true craftsmen and true artists that are making sculptures, that are doing camera work, lighting. As far as filmmaking, it's a whole crew, right there," said Hjartarson.

Contrary to popular belief, a lot of effects don't involve adding computer-generated objects or characters. Instead, they involve visually removing safety props used to create the scene.

The script for this commercial envisioned a huge truck being abducted by aliens. It was actually lifted by a crane but with the help of computer software, cables were simply erased from the picture.

Hjartarson says computers can erase anything without a trace.

“They can be robot rigs that actually may puppeteer a stunt person through a scene. They could be motion control for cameras - which is essentially a big robot that controls a camera that shoots the scene. Lighting rigs, whatever needs to get removed. We can even go so far as to remove and augment vanity items like enhancing physical features and proportions etcetera, which has been known to happen," he said.

Dangerous scenes used to be shot with stunt specialists rather than risk the movie stars. But since safety equipment can now be digitally erased, Mike Chambers, chairman of the Visual Effects Society Board of Directors, says many actors want to perform their own stunts.

“When you have Sandra Bullock, who's going to get on rig, there are stunt people who train her and make sure she knows exactly what she's doing, so she doesn't get hurt," said Chambers.

Still, it is not always easy to remove unwanted objects from the picture.

Effects specialist Isabelle Langlois, who worked on the award-winning film ‘Birdman,’ says advance planning can prevent many difficulties.

“The filmmakers are thinking about it from the early beginning and involving us on the shoot and visual effects work in establishing methodology and making sure that it's shot in a way that it's going to be easy to do it at the end in post-production," said Langlois.

Experts say with more sophisticated software and the ever-increasing speed of computer processors, moviegoers can expect to see their favorite stars in even more exciting scenes and situations.